Lineament Mapping and Groundwater Occurrence within the Vicinity of Osara Dam, Itakpe-Okene area, North Central Nigeria, Using Landsat Data

Abstract

The implementation of geographic information systems (GIS) tools and remote sensing data for exploration of groundwater in area with scarce water resources saves time and money. Digital layers of topographic, drainage, lithology, and geological structure maps were prepared and analyzed using remote sensing data and GIS tools; to identify the most promising sites for groundwater explorarion in the studied area. Lineament analysis of Osara area using LandSat MSS data was performed to identify linear geologic features and lineament density. Directional edge enhancement techniques using convolution kernel were applied to Band 5 to enhance lineament in NW, N-S and E-W compass directions which act as conduit for ground water recharge. The result indicates that NE-SW is the most predominant lineament trend and a few along NW-SE direction. The hydrogeomorphologic and groundwater potentiality of the area were studied using ILWIS 3.2 and Surfer 8 workstations. Hydrogeomorphological analyses of the area was also carried out using visual interpretation of true and false colour composite (FCC) imagery and field observations. A weigtage is assigned to each theme depending on its influence on the storage and movement of groundwater. A knowledge based ranking is assigned to each unit in every theme map, depending on its significance to groundwater occurrence. The cumulative scores have been worked out and the scored pattern has been contoured in preparing the final potential map and classified into five groundwater prospect categories which are further justified by hydrological studies. Based on groundwater potentiality zones, the study reveals that about 13% of the area has good potential; about 58% is moderately good while about 31% of the area has poor ground water potential. The central part reveals favourable environment for higher water yield as well as favourable discharge area for groundwater prospect. The study showed that remote sensing and GIS is an efficient tools for mapping an area for groundwater exploration.